Method for managing a memory apparatus

ABSTRACT

A method for managing a memory apparatus including at least one non-volatile (NV) memory element includes: recording valid/invalid page position information of at least one block; and moving valid data contained in at least a valid page of the block according to the valid/invalid page position information; where the block is an erasing unit. For example, the valid/invalid page position information may contain relative position information of the valid data in the block. More particularly, the valid/invalid page position information may contain a plurality of bits, the ranking of each bit may represent a page address offset of each page within the block, and each bit may respectively indicate whether each page in the block is valid or invalid.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. non-provisionalapplication Ser. No. 12/471,413, which was filed on May 25, 2009, and isentitled “METHOD FOR MANAGING A MEMORY APPARATUS, AND ASSOCIATED MEMORYAPPARATUS THEREOF”. In addition, U.S. non-provisional application Ser.No. 12/471,413 claims the benefit of U.S. provisional application No.61/112,173, which was filed on Nov. 6, 2008, and is entitled “METHOD FORBUILDING A LOGICAL-TO-PHYSICAL ADDRESS LINKING TABLE OF A MEMORYAPPARATUS”. Additionally, U.S. non-provisional application Ser. No.12/471,413 further claims the benefit of U.S. provisional applicationNo. 61/140,850, which was filed on Dec. 24, 2008, and entitled “METHODFOR MANAGING AND ACCESSING A STORAGE APPARATUS”.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to flash memory control, and moreparticularly, to a method for managing a memory apparatus, and anassociated memory apparatus thereof.

2. Description of the Prior Art

While a host is accessing a memory apparatus (e.g. a solid state drive,SSD), the host typically sends an accessing command and at least acorresponding logical address to the memory apparatus. The controller ofthe memory apparatus receives the logical address and transfers thelogical address into a physical address by utilizing alogical-to-physical address linking table. Thus, the controller accessesat least one physical memory element (or memory component) of the memoryapparatus by utilizing the physical address. For example, the memoryelement can be implemented with one or more flash memory chips (whichcan be referred to as flash chips for simplicity).

The logical-to-physical address linking table can be built in accordancewith a memory unit in the memory element. For example, thelogical-to-physical address linking table can be built by blocks or bypages. When the logical-to-physical address linking table is built byblocks, the logical-to-physical address linking table can be referred toas the logical-to-physical block address linking table. When thelogical-to-physical address linking table is built by pages, thelogical-to-physical address linking table can be referred to as thelogical-to-physical page address linking table. In addition, alogical-to-physical page address linking table comprising linkingrelationships about pages of a plurality of blocks (or all blocks) inthe memory apparatus can be referred to as the global page addresslinking table.

Assume that the memory element has X physical blocks, and each physicalblock has Y physical pages. In a situation where the logical-to-physicaladdress linking table is built by blocks, the associatedlogical-to-physical block address linking table can be built by readinga logical block address stored in a page of each physical block andrecording the relationship between the physical block and the associatedlogical block. In order to build the logical-to-physical block addresslinking table, X pages respectively corresponding to the X physicalblocks have to be read, where the time required for this is assumed tobe x seconds.

In a situation where the logical-to-physical address linking table isbuilt by pages, the associated global page address linking table can bebuilt by reading a logical page address stored in each physical page ofall physical blocks and recording the relationship between the physicalpage and the associated logical page. In order to build the global pageaddress linking table, at least X·Y pages have to be read, requiring x·Yseconds. If a block has 1024 pages, the time required for building theglobal page address linking table is 1024 times the time required forbuilding the logical-to-physical block address linking table, i.e.1024·x seconds, which is an unacceptable processing time since theprocessing speed is too slow. That is, when implementing the global pageaddress linking table in this way, the overall performance of accessingthe memory apparatus is retarded. Therefore, a novel method is requiredfor efficiently building the logical-to-physical address linking table,and related methods for managing memory apparatus operated under thenovel method is required.

SUMMARY OF THE INVENTION

It is therefore an objective of the present invention to provide amethod for managing a memory apparatus, and to provide an associatedmemory apparatus thereof, in order to solve the above-mentioned problem.

It is another objective of the present invention to provide a method formanaging a memory apparatus, and to provide an associated memoryapparatus thereof, in order to optimize the arrangement of a spareregion and a data region of the memory apparatus.

According to at least one preferred embodiment of the present invention,a method for managing a memory apparatus is disclosed. The memoryapparatus comprises at least one non-volatile (NV) memory element, eachof which comprises a plurality of blocks comprising a plurality ofpages, respectively. The method comprises: recording valid/invalid pageposition information of at least one block; and moving valid datacontained in at least a valid page of the block according to thevalid/invalid page position information; wherein the block is an erasingunit. For example, the valid/invalid page position information containsrelative position information of the valid data in the block. Moreparticularly, the valid/invalid page position information contains aplurality of bits, the ranking of each bit represents a page addressoffset of each page within the block, and each bit respectivelyindicates whether each page in the block is valid or invalid.

It is an advantage of the present invention that, in contrast to therelated art, the present invention method and apparatus can greatly savethe time of building logical-to-physical address linking table(s), suchas the time of building a logical-to-physical page address linkingtable. Therefore, the present invention provides better performance thanthe related art.

It is another advantage of the present invention that the presentinvention method and apparatus can record the usage information duringaccessing the pages, and therefore can efficiently manage the usage ofall blocks according the usage information. As a result, the arrangementof the spare region and the data region can be optimized.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a memory apparatus according to a firstembodiment of the invention.

FIG. 2A illustrates a local page address linking table within a block ofone of the NV memory elements shown in FIG. 1, where the NV memoryelement of this embodiment is a flash chip.

FIG. 2B compares the one-dimensional (1-D) array illustration and thetwo-dimensional (2-D) array illustration of the local page addresslinking table shown in FIG. 2A.

FIGS. 3A-3F respectively illustrate exemplary versions of a global pageaddress linking table of the memory apparatus shown in FIG. 1 accordingto an embodiment of the present invention.

FIG. 4 illustrates a local page address linking table within a block ofthe flash chip shown in FIG. 2A according to an embodiment of thepresent invention.

FIGS. 5A-5B respectively illustrate exemplary versions of the globalpage address linking table of the memory apparatus shown in FIG. 1according to the embodiment shown in FIG. 4.

FIG. 6 illustrates an arrangement of one of the NV memory elements shownin FIG. 1 according to an embodiment of the present invention, where theNV memory element of this embodiment is a flash chip.

FIGS. 7A-7D illustrate physical addresses of the NV memory elementsshown in FIG. 1 according to an embodiment of the invention, where theNV memory elements of this embodiment are a plurality of flash chips.

FIG. 8 illustrates a data region and a spare region for managing theflash chips shown in FIGS. 7A-7D.

FIGS. 9A-9D respectively illustrate exemplary versions of a global pageaddress linking table of the embodiment shown in FIGS. 7A-7D.

FIGS. 10A-10F respectively illustrate exemplary versions of a valid pagecount table of the embodiment shown in FIGS. 7A-7D.

FIG. 11 illustrates a valid-page-position table of the flash chips shownin FIGS. 7A-7D according to an embodiment of the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 1, which illustrates a block diagram of a memoryapparatus 100 according to a first embodiment of the invention. Thememory apparatus 100 comprises a processing unit 110, a volatile memory120, a transmission interface 130, a plurality of non-volatile (NV)memory elements 140_0, 140_1, . . . , and 140_N (e.g. flash chips), anda bus 150. Typically, a host (not shown in FIG. 1) can be arranged toaccess the memory apparatus 100 through the transmission interface 130after the transmission interface 130 is coupled to the host. Forexample, the host can represent a personal computer such as a laptopcomputer or a desktop computer.

The processing unit 110 is arranged to manage the memory apparatus 100according to a program code (not shown in FIG. 1) embedded in theprocessing unit 110 or received from outside the processing unit 110.For example, the program code can be a hardware code embedded in theprocessing unit 110, such as a ROM code. In another example, the programcode can be a firmware code received from outside the processing unit110. More particularly, the processing unit 110 is utilized forcontrolling the volatile memory 120, the transmission interface 130, theNV memory elements 140_0, 140_1, . . . , and 140_N, and the bus 150. Theprocessing unit 110 of this embodiment can be an ARM processor or an ARCprocessor. This is for illustrative purposes only, and is not meant tobe a limitation of the present invention. According to differentvariations of this embodiment, the processing unit 110 can be otherkinds of processors.

In addition, the volatile memory 120 is utilized for storing a globalpage address linking table, data accessed by the host (not shown), andother required information for accessing the memory apparatus 100. Thevolatile memory 120 of this embodiment can be a DRAM or an SRAM. This isfor illustrative purposes only, and is not meant to be a limitation ofthe present invention. According to different variations of thisembodiment, the volatile memory 120 can be other kinds of volatilememories.

According to this embodiment, the transmission interface 130 shown inFIG. 1 is utilized for transmitting data and commands between the hostand the memory apparatus 100, where the transmission interface 130complies with a particular communication standard such as the SerialAdvanced Technology Attachment (SATA) standard, the Parallel AdvancedTechnology Attachment (PATA) standard, or the Universal Serial Bus (USB)standard. For example, the memory apparatus 100 is a solid state drive(SSD) installed within the host, and the particular communicationstandard can be some communication standard typically utilized forimplementing internal communication of the host, such as the SATAstandard or the PATA standard. In another example, the memory apparatus100 is an SSD and is positioned outside the host, and the particularcommunication standard can be some communication standard typicallyutilized for implementing external communication of the host, such asthe USB standard. This is for illustrative purposes only, and is notmeant to be a limitation of the present invention. According todifferent variations of this embodiment, the memory apparatus 100 can bea portable memory device such as a memory card, and the particularcommunication standard can be some communication standards typicallyutilized for implementing an input/output interface of a memory card,such as the Secure Digital (SD) standard or the Compact Flash (CF)standard.

In addition, the NV memory elements 140_0, 140_1, . . . , and 140_N areutilized for storing data, where the NV memory elements 140_0, 140_1, .. . , and 140_N can be, but not limited to, NAND flash chips. The bus150 is utilized for coupling the processing unit 110, the volatilememory 120, the transmission interface 130, and the NV memory elements140_0, 140_1, . . . , and 140_N, and for communication thereof.

According to this embodiment, the processing unit 110 can provide atleast one block of the memory apparatus 100 with at least one local pageaddress linking table within the memory apparatus 100, where the localpage address linking table comprises linking relationships betweenphysical page addresses and logical page addresses of a plurality ofpages. In this embodiment, the processing unit 110 builds the local pageaddress linking table during programming/writing operations of thememory apparatus 100. The processing unit 110 can further build theglobal page address linking table mentioned above according to the localpage address linking table. For example, the processing unit 110 reads afirst linking relationship between a first physical page address and afirst logical page address from the at least one local page addresslinking table, and then records the first linking relationship into theglobal page address linking table. The processing unit 110 can furtherread a second linking relationship between a second physical pageaddress and the first logical page address from the at least one localpage address linking table, and then record the second linkingrelationship into the global page address linking table in order toupdate the global page address linking table.

More particularly, the processing unit 110 provides a plurality ofblocks of the memory apparatus 100 with a plurality of local pageaddress linking tables within the memory apparatus 100, respectively.That is, the aforementioned at least one local page address linkingtable comprises a plurality of local page address linking tables. Theprocessing unit 110 can further build the global page address linkingtable mentioned above according to the local page address linkingtables. More specifically, the processing unit 110 can read one of thelocal page address linking tables to update the global page addresslinking table mentioned above. For example, the first linkingrelationship of a first physical page is read from a first local pageaddress linking table of the local page address linking tables, and thesecond linking relationship of a second physical page is read from asecond local page address linking table of the local page addresslinking tables. Implementation details of the local page address linkingtables are further described by referring to FIG. 2A.

FIG. 2A illustrates a local page address linking table within a block ofthe NV memory element 140_0, where the NV memory element 140_0 of thisembodiment is referred to as a flash chip 0 for simplicity. As shown inFIG. 2A, the flash chip 0 comprises a plurality of blocks, such asblocks 0, 1, 2, . . . , M in this embodiment. Please note that a blockis an erasing unit. In other words, when erasing data is required, theprocessing unit 110 erases all data stored in the block at a time. Inaddition, a block, such as the block 0 shown in FIG. 2A, comprises aplurality of pages. For example, the block 0 of the flash chip 0comprises 128 pages. Within a block such as the block 0, the pages aredivided into two areas, a data area for storing data and a table areafor storing a local page address linking table 0. The pages in the dataarea of the block can be referred to as the data pages of the block.

According to this embodiment, the page amount of the data area and thepage amount of the table area can be determined as required. Forexample, pages 0, 1, 2, . . . , 126 is utilized for storing data and theremaining page of the block is utilized for storing the local pageaddress linking table 0. This is for illustrative purposes only, and isnot meant to be a limitation of the present invention. According to avariation of this embodiment, the data area may comprise less than 127pages, and the table area may comprise two or more pages. According toanother variation of this embodiment, the total page amount of theblock, the page amount of the data area, and the page amount of thetable area may vary. Please note that a page is a programming/writingunit. In other words, when programming/writing data is required, theprocessing unit 110 programs/writes a page of data into a page at atime. According to this embodiment, the NV memory elements 140_0, 140_1,. . . , and 140_N shown in FIG. 1 are respectively referred to as theflash chips 0, 1, . . . , and N, where each block of the NV memoryelements 140_0, 140_1, . . . , 140_N may have a local page addresslinking table. For simplicity, only the local page address linking table0 of the block 0 of the flash chip 0 is illustrated in FIG. 2A since thefunctions/operations of each local page address linking table aresimilar to each other.

In this embodiment, the local page address linking table 0 is built whenall the data pages in the block 0 have been programmed, namely fullyprogrammed. Before the data pages in the block 0 are fully programmed,however, the processing unit 110 temporarily stores a temporary localpage address linking table 0 in the volatile memory 120, and furtherupdates the temporary local page address linking table 0 when anylinking relationship between a physical page address and a logical pageaddress in the block 0 is changed.

According to this embodiment, the ranking of a field (entry) of thetemporary/non-temporary local page address linking table (e.g. thetemporary local page address linking table 0 or the local page addresslinking table 0) represents a physical page address, and the content ofthis field represents an associated logical page address. For example,suppose that i_(P) and j_(P) are respectively the row number and thecolumn number of the illustrative table location (i_(P), j_(P)) of thetemporary/non-temporary local page address linking table shown in FIG.2A and i_(P)=0, 1, . . . , etc. and j_(P)=0, 1, . . . , etc. In thistwo-dimensional (2-D) array illustration of the temporary/non-temporarylocal page address linking table shown in FIG. 2A, the illustrativetable location (i_(P), j_(P)) corresponding to the (i_(P)*4+j_(P))^(th)field represents a physical page address PPN, which can be described asfollows:

PPN=(PBN*DPC+i _(P)*4+j _(P));

where the notation PBN stands for the physical block number of thephysical block under discussion (e.g. PBN=0, 1, 2, . . . , etc. for theblocks 0, 1, 2, . . . , etc., respectively), and the notation DPC standsfor the data page count of each block (e.g. 127 in this embodiment).This is for illustrative purposes only, and is not meant to be alimitation of the present invention. For better comprehension, thetemporary/non-temporary local page address linking table can beillustrated as a single column, as shown in the right half of FIG. 2B,where “PHY Page” stands for “physical page”, and “LOG Page” stands for“logical page”. Given that i_(P) is still the row number and i_(P)=0, 1,. . . , etc., within the temporary/non-temporary local page addresslinking table of the block PBN of this one-dimensional (1-D) arrayillustration shown in the right half of FIG. 2B, the illustrative tablelocation i_(P) corresponding to the i_(P) ^(th) field represents aphysical page address (PBN*DPC+i_(P)). That is, for this 1-D arrayillustration, the above equation can be re-written as follows:

PPN=(PBN*DPC+i _(P)).

Please note that, in this embodiment, a range of the logical pageaddresses in the local page address linking table 0 is not greater thanthe number of pages in the block 0 (i.e. 128 in this embodiment). Thisis for illustrative purposes only, and is not meant to be a limitationof the present invention. According to a variation of this embodiment, arange of the logical page addresses in a local page address linkingtable such as the local page address linking table 0 can be greater thanthe number of pages in a block such as the block 0.

Within the temporary local page address linking table 0 or the localpage address linking table 0 shown in FIG. 2A, the illustrative tablelocation (0, 0) (i.e. the upper-left location) corresponding to thefirst field represents the physical page address 0x0000, theillustrative table location (0, 1) corresponding to the second fieldrepresents the physical page address 0x0001, the illustrative tablelocation (0, 2) corresponding to the third field represents the physicalpage address 0x0002, the illustrative table location (0, 3)corresponding to the fourth field represents the physical page address0x0003, the illustrative table location (1, 0) corresponding to thefifth field represents the physical page address 0x0004, and so on.

According to the embodiment shown in FIG. 2A, when the host sends acommand 0 to the processing unit 110 in order to program data 0 at alogical page address 0x0002, the processing unit 110 programs the data 0and the logical page address 0x0002 into the page 0 of the block 0 ofthe flash chip 0, wherein the data 0 is programmed in a data byte region(labeled “DBR”) of the page 0, and the logical page address 0x0002 isprogrammed in a spare byte region (labeled “SBR”) of the page 0 as spareinformation. In addition, the processing unit 110 writes the logicalpage address 0x0002 into the first field of the temporary local pageaddress linking table 0 (or the illustrative table location (0, 0)thereof in this embodiment, i.e. the illustrative table location of thefirst column and the first row) to thereby indicate that the logicalpage address 0x0002 links/maps to the page 0 of the block 0 of the flashchip 0, whose physical page address is 0x0000.

Similarly, when the host then sends a command 1 to the processing unit110 in order to program data 1 at a logical page address 0x0001, theprocessing unit 110 programs the data 1 and the logical page address0x0001 into the page 1 of the block 0 of the flash chip 0, wherein thedata 1 is programmed in a data byte region (labeled “DBR”) of the page1, and the logical page address 0x0001 is programmed in a spare byteregion (labeled “SBR”) of the page 1 as spare information. In addition,the processing unit 110 writes the logical page address 0x0001 into thesecond field of the temporary local page address linking table 0 (or theillustrative table location (0, 1) thereof in this embodiment, i.e. theillustrative table location of the second column and the first row) tothereby indicate that the logical page address 0x0001 links/maps to page1 of block 0 of flash chip 0, whose physical page address is 0x0001.Afterward, when the host sends a command 2 to the processing unit 110 inorder to program data 2 at the logical page address 0x0002 again, theprocessing unit 110 programs the data 2 and the logical page address0x0002 into the page 2 of the block 0, wherein the data 2 is programmedin a data byte region (labeled “DBR”) of the page 2, and the logicalpage address 0x0002 is programmed in a spare byte region (labeled “SBR”)of the page 2 as spare information. In addition, the processing unit 110writes the logical page address 0x0002 into the third field of thetemporary local page address linking table 0 (or the illustrative tablelocation (0, 2) thereof in this embodiment, i.e. the illustrative tablelocation of the third column and the first row) to thereby update thatthe logical page address 0x0002 links/maps to the page 2 of the block 0of the flash chip 0, whose physical page address is 0x0002. Similaroperations for the subsequent pages are not repeated in detail forsimplicity.

As a result of the above operations, referring to the upper-rightportion of FIG. 2A, a serial of logical page addresses {0x0002, 0x0001,0x0002, 0x0005, 0x0003, 0x0007, 0x0010, 0x0008, . . . , 0x0000, 0x0009,0x0004} are written in the temporary local page address linking table 0.When all the data pages in the block 0 (i.e. pages 0, 1, 2, . . . , 126in this embodiment) have been programmed, the processing unit 110 copiesthe temporary local page address linking table 0 to build the local pageaddress linking table 0. More specifically, the processing unit 110programs the local page address linking table 0 into the table area(i.e. the remaining page 127) of the block 0 of the flash chip 0 in thisembodiment. This is for illustrative purposes only, and is not meant tobe a limitation of the present invention. According to a variation ofthis embodiment, the processing unit 110 can program a local pageaddress linking table for a portion of data pages in a block, ratherthan all data pages of the block.

In this variation, after programming a first portion of data pages of aspecific block, the processing unit 110 can program a first local pageaddress linking table for the first portion of data pages, where thefirst local page address linking table is positioned next to the firstportion of data pages. After programming a second portion of data pagesof the specific block, the processing unit 110 can program a secondlocal page address linking table for the second portion of data pages.For example, the second local page address linking table is positionednext to the second portion of data pages. In another example, the secondlocal page address linking table is positioned at the end (e.g. the lastpage) of the specific block. In another example, the second local pageaddress linking table is positioned at the beginning (e.g. the firstpage) of the block next to the specific block. In another example, thesecond local page address linking table is positioned at another page(or other pages) of the block next to the specific block.

FIGS. 3A-3F respectively illustrate exemplary versions of theaforementioned global page address linking table of the memory apparatus100 according to an embodiment of the present invention. When buildingthe global page address linking table of the memory apparatus 100, theprocessing unit 110 reads each of the local page address linking tablesrespectively corresponding to the blocks of the memory apparatus 100 tobuild the global page address linking table. For example, within thememory apparatus 100, if only the blocks 0 and 1 of the flash chip 0have been fully programmed, and if the local page address linking table0 in the block 0 and the local page address linking table 1 in the block1 have been built, the processing unit 110 reads the local page addresslinking tables 0 and 1 to build the global page address linking table.

According to this embodiment, referring to the left half of FIG. 3Afirst, the ranking of a field of the global page address linking tablerepresents a logical page address, and the content of this fieldrepresents an associated physical page address. For example, given thati_(L) and j_(L) are respectively the row number and the column number ofthe illustrative table location (i_(L), j_(L)) of the global pageaddress linking table shown in the left half of FIGS. 3A and i_(L)=0, 1,. . . , etc. and j_(L)=0, 1, . . . , etc. in this 2-D arrayillustration, the illustrative table location (i_(L), j_(L))corresponding to the (i_(L)*4+j_(L))^(th) field represents a logicalpage address (i_(L)*4+j_(L)). This is for illustrative purposes only,and is not meant to be a limitation of the present invention. For bettercomprehension, the global page address linking table can be illustratedas a single column, as shown in the right half of FIG. 3A. Given thati_(L) is still the row number and i_(L)=0, 1, . . . , etc., within this1-D array illustration of the global page address linking table, theillustrative table location i_(L) corresponding to the i_(L) ^(th) fieldrepresents a logical page address i_(L).

Within the global page address linking table shown in the left half ofFIG. 3A, the illustrative table location (0, 0) (i.e. the upper-leftlocation) corresponding to the first field represents the logical pageaddress 0x0000, the illustrative table location (0, 1) corresponding tothe second field represents the logical page address 0x0001, theillustrative table location (0, 2) corresponding to the third fieldrepresents the logical page address 0x0002, the illustrative tablelocation (0, 3) corresponding to the fourth field represents the logicalpage address 0x0003, the illustrative table location (1, 0)corresponding to the fifth field represents the logical page address0x0004, and so on.

When building the global page address linking table, the processing unit110 reads the first field of the local page address linking table 0shown in FIG. 2A and obtains the logical page address 0x0002, andtherefore determines that the logical page address 0x0002 links to thepage 0 of the block 0 of the flash chip 0, whose physical page addressis 0x0000. As shown in FIG. 3A, the processing unit 110 writes thephysical page address 0x0000 (PHY Page 0x0000) into the third field ofthe global page address linking table (i.e. the illustrative tablelocation (0, 2) of the 2-D array illustration thereof) to indicate thatthe logical page address 0x0002 (LOG Page 0x0002) links to the physicalpage address 0x0000.

Next, the processing unit 110 reads the second field of the local pageaddress linking table 0 shown in FIG. 2A and obtains the logical pageaddress 0x0001, and therefore determines that the logical page address0x0001 links to the page 1 of the block 0 of the flash chip 0, whosephysical page address is 0x0001. As shown in FIG. 3B, the processingunit 110 writes the physical page address 0x0001 into the second fieldof the global page address linking table to indicate that the logicalpage address 0x0001 (LOG Page 0x0001) links to the physical page address0x0001 (PHY Page 0x0001).

Then, the processing unit 110 reads the third field of the local pageaddress linking table 0 shown in FIG. 2A and obtains the logical pageaddress 0x0002, and therefore determines that the logical page address0x0002 links to the page 2 of the block 0 of the flash chip 0, whosephysical page address is 0x0002. As shown in FIG. 3C, the processingunit 110 writes (or updates) the physical page address 0x0002 into thethird field of the global page address linking table to indicate thatthe logical page address 0x0002 (LOG Page 0x0002) links to the physicalpage address 0x0002 (PHY Page 0x0002).

Subsequently, the processing unit 110 reads the fourth field of thelocal page address linking table 0 shown in FIG. 2A and obtains thelogical page address 0x0005, and therefore determines that the logicalpage address 0x0005 links to the page 3 of the block 0 of the flash chip0, whose physical page address is 0x0003. As shown in FIG. 3D, theprocessing unit 110 writes the physical page address 0x0003 into thesixth field of the global page address linking table to indicate thatthe logical page address 0x0005 (LOG Page 0x0005) links to the physicalpage address 0x0003 (PHY Page 0x0003).

Afterward, the processing unit 110 reads the fifth field of the localpage address linking table 0 shown in FIG. 2A and obtains the logicalpage address 0x0003, and therefore determines that the logical pageaddress 0x0003 links to the page 4 of the block 0 of the flash chip 0,whose physical page address is 0x0004. As shown in FIG. 3E, theprocessing unit 110 writes the physical page address 0x0004 into thefourth field of the global page address linking table to indicate thatthe logical page address 0x0003 (LOG Page 0x0003) links to the physicalpage address 0x0004 (PHY Page 0x0004). Similar operations for thesubsequent linking relationships are not repeated in detail. Afterreading all fields of the local page address linking table 0 shown inFIG. 2A and filling the corresponding physical page addresses into theassociated fields of the global page address linking table, theprocessing unit 110 builds the global page address linking table asshown in FIG. 3F.

FIG. 4 illustrates the local page address linking table 1 within theblock 1 of the flash chip 0 according to an embodiment of the presentinvention. After reading all fields of the local page address linkingtable 0 shown in FIG. 2A and filling the corresponding physical pageaddresses into the associated fields of the global page address linkingtable as shown in FIG. 3F, the processing unit 110 further reads thelocal page address linking table 1 within the block 1 in order tocomplete the global page address linking table. Please note that, inthis embodiment, the local page address linking table 1 is built whenall data pages in the block 1 have been programmed. This is forillustrative purposes only, and is not meant to be a limitation of thepresent invention. According to a variation of this embodiment, a localpage address linking table can be built for a block when at least a datapage (e.g. a data page or a plurality of pages) in this block have beenprogrammed. In this variation, the local page address linking table isbuilt for this block, and more particularly, for at least the data page.For example, the local page address linking table is built for a fewdata pages such as physical pages 0 and 1 of this block, where the localpage address linking table for the physical pages 0 and 1 is built andstored in the subsequent physical page, i.e. the physical page 2. Whenbuilding (or updating) the global page address linking table, in asituation where there is no local page address linking table found inthe last page of this block, the processing unit 110 tries to find thelast programmed page of this block. In this variation, the processingunit 110 searches back, starting from the last page, in order to findthe last programmed page of this block. As a result, the processing unit110 reads all fields of the local page address linking table from thelast programmed page of this block and fills the corresponding physicalpage addresses into the associated fields of the global page addresslinking table, in order to complete/update the global page addresslinking table.

According to the embodiment shown in FIG. 4, the processing unit 110reads the first field of the local page address linking table 1 andobtains the logical page address 0x0006, and therefore determines thatthe logical page address 0x0006 links to the page 0 of the block 1 ofthe flash chip 0, whose physical page address is 0x0127 in thisembodiment. As shown in FIG. 5A, the processing unit 110 writes thephysical page address 0x0127 into the seventh field of the global pageaddress linking table to indicate that the logical page address 0x0006(LOG Page 0x0006) links to the physical page address 0x0127 (PHY Page0x0127).

Next, the processing unit 110 reads the second field of the local pageaddress linking table 1 shown in FIG. 4 and obtains the logical pageaddress 0x0002, and therefore determines that the logical page address0x0002 links to the page 1 of the block 1 of the flash chip 0, whosephysical page address is 0x0128. As shown in FIG. 5B, the processingunit 110 writes (or updates) the physical page address 0x0128 into thethird field of the global page address linking table to indicate thatthe logical page address 0x0002 (LOG Page 0x0002) links to the physicalpage address 0x0128 (PHY Page 0x0128). Similar operations for thesubsequent linking relationships are not repeated in detail. Afterreading all fields of the local page address linking tables 0 and 1 andfilling the corresponding physical page addresses into the associatedfields of the global page address linking table, the processing unit 110completes the global page address linking table.

Instead of reading all pages (or memory units) of the NV memory elements140_0, 140_1, . . . , and 140_N to build the global page address linkingtable, the processing unit 110 of this embodiment merely reads a fewnumber of local page address linking tables within (or representing butnot within) the blocks that are fully or partially programmed.Therefore, the memory apparatus implemented according to the presentinvention surely have better efficiency than those implemented accordingto the related art.

According to a variation of this embodiment, in a situation where alldata pages of all data blocks of the NV memory elements 140_0, 140_1, .. . , and 140_N are fully programmed, the processing unit 110 merelyreads the local page address linking tables respectively correspondingto the data blocks to build the global page address linking table. Ifthe NV memory elements 140_0, 140_1, . . . , and 140_N have X_(D) datablocks in total, and each data block has Y_(D) data pages, theprocessing unit 110 reads X_(D) local page address linking tables (whosedata amount is typically less than X_(D) pages in total) to build theglobal page address linking table, rather than reading X_(D)·Y_(D)pages. In other words, the time required for building the global pageaddress linking table according to the present invention is similar tothe time required for building the global block address linking table.

According to another variation of this embodiment, in a situation wherea particular block is not fully programmed (i.e. the particular block ispartially programmed), at one time there is no local page addresslinking table within the particular block. In the volatile memory 120,however, there is a temporary local page address linking table of theparticular block. The processing unit 110 of this variation canprogram/write the temporary local page address linking table to theparticular block before shutting down the memory apparatus 100. Forexample, after the memory apparatus 100 begins a start-up process, thehost can read the local page address linking table stored in theparticular block, in order to build or update the global page addresslinking table. This is for illustrative purposes only, and is not meantto be a limitation of the present invention. In another example, afterthe memory apparatus 100 begins a start-up process, the processing unit110 can read the pages programmed in the particular block, and moreparticularly, the spare byte region of each page programmed in theparticular block, in order to build or update the global page addresslinking table.

In a situation where the processing unit 110 reads the pages programmedin the particular block to build or update the global page addresslinking table, the processing unit 110 has to read less than Y_(D) pagesof data from the particular block. As a result, for completing theglobal page address linking table, the data amount that the processingunit 110 has to read is less than (X_(FP)+Y_(PP)) pages, given that theNV memory elements 140_0, 140_1, . . . , and 140_N have X_(FP) fullyprogrammed blocks in total and further have a partially programmed blockhaving Y_(PP) programmed data pages. Therefore, in regard to buildingthe global page address linking table, the memory apparatus implementedaccording to the present invention still have better efficiency thanthose implemented according to the related art.

According to different variations of the embodiments mentioned above,the global page address linking table can be built during any start-upprocess of the memory apparatus 100 or at any time in response to arequest from a user.

According to different variations of the embodiments mentioned above,the global page address linking table can be divided into a plurality ofpartial tables stored in one or more of the NV memory elements (e.g. thepartial tables are respectively stored in the NV memory elements 140_0,140_1, . . . , and 140_N). Each divided partial table can be referred asa sub-global page address linking table. The processing unit 110 canread and store at least one sub-global page address linking table (e.g.a sub-global page address linking table, some sub-global page addresslinking tables, or all the sub-global page address linking tables) ofthe global page address linking table into the volatile memory 120,depending on the size of the global page address linking table and thesize of the volatile memory 120 or depending on some requirements. Theprocessing unit 110 can utilize the sub-global page address linkingtable stored in the volatile memory 120 to perform thelogical-to-physical address transferring operations of theaforementioned embodiments.

FIG. 6 illustrates an arrangement of the NV memory element 140_0according to an embodiment of the present invention, where the NV memoryelement 140_0 of this embodiment is referred to as the flash chip 0 asmentioned above. As shown in FIG. 6, a page comprises a plurality ofsectors, e.g. sectors 0, 1, 2, and 3. A sector is the minimal read unit,which can be 512 bytes in this embodiment. In other words, theprocessing unit 110 can read one sector or a plurality of sectors duringa reading operation.

FIGS. 7A-7D illustrate the physical addresses of the flash chips 0, 1, .. . , and N according to an embodiment of the invention, where N=3 andM=1023 in this embodiment. As the physical addresses of this embodimentmay fall within a range that is wider than the range [0x0000, 0xFFFF]utilized in some embodiments disclosed above, the physical addresses areillustrated with the decimal numeral system hereinafter for simplicity.This is for illustrative purposes only, and is not meant to be alimitation of the present invention. According to a variation of thisembodiment, the physical addresses can be illustrated with thehexadecimal numeral system, where the physical addresses may have moredigits than those in some embodiments disclosed above. According toanother variation of this embodiment, the physical addresses can beillustrated with another numeral system when needed.

Regarding the physical block addresses, the first block of the flashchip 0 is regarded as the first block of the flash chips 0-3, and isaddressed as the physical block address 0, and therefore, can bereferred to as PHY BLK 0, where “PHY BLK” stands for “physical block”.The last block of the flash chip 0 is regarded as the 1024^(th) block ofthe flash chips 0-3, and is addressed as the physical block address1023, and therefore, can be referred to as PHY BLK 1023. The first blockof the flash chip 1 is regarded as the 1025^(th) block of the flashchips 0-3, and is addressed as the physical block address 1024, andtherefore, can be referred to as PHY BLK 1024, and so on. The last blockof the flash chip 3 is regarded as the 4096^(th) block of the flashchips 0-3, and is addressed as the physical block address 4095, andtherefore, can be referred to as PHY BLK 4095. In this embodiment, theblocks of the flash chips 0-3 comprise 4 sets of PHY BLKs {0, 1, . . . ,1023}, {1024, 1025, . . . , 2047}, {2048, 2049, . . . , 3071}, and{3072, 3073, . . . , 4095}, i.e. 4096 PHY BLKs in total.

Regarding the physical page addresses, the first page of PHY BLK 0 isregarded as the first page of the flash chips 0-3, and is addressed asthe physical page address 0, and therefore, can be referred to as PHYPage 0. The last page of PHY BLK 0 is regarded as the 128^(th) page ofthe flash chips 0-3, and is addressed as the physical page address 127,and therefore, can be referred to as PHY Page 127. The first page of PHYBLK 1 is regarded as the 129^(th) page of the flash chips 0-3, and isaddressed as the physical page address 128, and therefore, can bereferred to as PHY Page 128, and so on. The last page of PHY BLK 4095 isregarded as the 524288^(th) page of the flash chips 0-3, and isaddressed as the physical page address 524287, and therefore, can bereferred to as PHY Page 524287. In this embodiment, the pages of theflash chips 0-3 comprise 4096 sets of PHY Pages {0, 1, . . . , 127},{128, 129, . . . , 255}, . . . , and {524160, 524161, . . . , 524287},i.e. 524288 PHY Pages in total.

FIG. 8 illustrates a data region and a spare region for managing theflash chips 0-3 shown in FIGS. 7A-7D. As shown in FIG. 8, the flashchips 0-3 are logically divided into the data region and the spareregion. The data region is utilized for storing data, and may initiallycomprise PHY BLKs 2, 3, . . . , and 4095. The spare region is utilizedfor writing new data, where the spare region typically comprises erasedblocks, and may initially comprise PHY BLKs 0 and 1. After a lot ofaccessing operations, the spare region may logically comprise adifferent set of physical blocks, and the data region may logicallycomprise the other physical blocks. For example, after a lot ofaccessing operations, the spare region may comprise PHY BLKs 4094 and4095, and the data region may comprise PHY BLKs 0-4093. In anotherembodiment, the spare region may comprise PHYs BLK 0, 1024, 2048, and3096, i.e. each of the flash chips 0-3 comprises at least a blocklogically belonging to the spare region. Please note that the number ofblocks of the data region and the number of blocks of the spare regioncan be determined based upon user/designer requirements. For example,the spare region may comprise 4 PHY BLKs, and the data region maycomprise 4092 PHY BLKs.

During writing/programming operations, the host sends a command C0 tothe memory apparatus 100 in order to write 4 sectors of data,D_(S0)-D_(S3), at corresponding host addresses 0000008-0000011. Thevolatile memory 120 temporarily stores data D_(S0)-D_(S3). Theprocessing unit 110 parses the command C0 to execute thewriting/programming operation corresponding to the command C0. Theprocessing unit 110 transfers the host addresses 0000008-0000011 intoassociated logical addresses. The processing unit 110 divides the hostaddress 0000008 by the number of sectors of a page, i.e. 4 in thisembodiment, and obtains a quotient 2 and a remainder 0. The quotient 2means that the logical page address thereof is 2, and therefore, thelogical page indicated by the logical page address 2 can be referred toas LOG Page 2. In addition, the remainder 0 means that the data D_(S0)should be stored in a first sector of a page. The processing unit 110further divides the host address 0000008 by the number of sectors of ablock, i.e. 512 in this embodiment, and obtains a quotient 0 and aremainder 8. The quotient 0 means that the logical block address thereofis 0, and therefore, the logical block indicated by the logical blockaddress 0 can be referred to as LOG BLK 0, where “LOG BLK” stands for“logical block”.

In practice, when the host address is expressed with the binary numeralsystem, the dividing operations can be performed by truncating a portionof bits of the host address. For example, when dividing the host address0000008 by 4, the processing unit 110 extracts the last two bits (i.e.two adjacent/continuous bits including the least significant bit (LSB))from the binary expression of the host address to obtain the remainder0, and extracts the other bits from this binary expression to obtain thequotient 2. In addition, when dividing the host address 0000008 by 512,the processing unit 110 can extract the last nine bits (i.e. nineadjacent/continuous bits including the LSB) from the binary expressionof the host address to obtain the remainder 8, and extract the otherbits from this binary expression to obtain the quotient 0. Therefore, inthis embodiment, the host address 0000008 substantially comprises thelogical page address 2 and the logical block address 0. Please notethat, as the host address 0000008 inherently belongs to LOG Page 2 andinherently belongs to LOG BLK 0, the processing unit 110 of a variationof this embodiment can parse the host address 0000008 by bit-shifting,rather than really performing the dividing operations.

Similarly, the processing unit 110 of this embodiment determines thatthe logical page addresses of the host addresses 0000009, 0000010, and0000011 are all 2 (i.e. all of the host addresses 0000009, 0000010, and0000011 inherently belong to LOG Page 2, or comprise the logical pageaddress 2), and the logical block addresses thereof are all 0 (i.e. allof the host addresses 0000009, 0000010, and 0000011 further inherentlybelong to LOG BLK 0, or comprise the logical block address 0). Inaddition, the data D_(S1), D_(S2), and D_(S3) should be respectivelystored in the second, the third, and the fourth sectors of a page.

In this embodiment, PHY BLK 0 is erased and is logically positioned inthe spare region initially, the processing unit 110 pops the PHY BLK 0from the spare region, and writes/programs the data D_(S0)-D_(S3) intothe first, the second, the third, and the fourth sectors of PHY Page 0,respectively. The processing unit 110 further records 0 in the thirdfield of the global page address linking table of this embodiment, inorder to indicate that LOG Page 2 links to PHY Page 0. FIGS. 9A-9Drespectively illustrate exemplary versions of the global page addresslinking table of this embodiment. The arrangement of the illustrativetable locations of this embodiment is similar to that of FIGS. 3A-3F,and therefore, is not explained in detail for simplicity. Referring tothe global page address linking table shown in FIG. 9A, the physicalpage address 0 has been written in the third field, which indicates thatLOG Page 2 links to PHY Page 0. Alternatively, the physical page address0 can be written in a corresponding field of a temporary local pageaddress linking table thereof for indicating the linking relationship ofthe logical and physical addresses. Then, the global page addresslinking table can be updated accordingly. The implementation details ofupdating the global page address linking table according to thetemporary local page address linking table are similar to those of theembodiments mentioned above. For simplicity, the following embodimentsonly illustrate that the global page address linking table is updatedfor reflecting a new logical-to-physical page address linkingrelationship, however, those skilled in the art will appreciate that thetemporary local page address linking table can be updated for reflectingthe new logical-to-physical page address linking relationship whenobtaining the teachings disclosed in the embodiments of the invention.Therefore, related descriptions are omitted.

In addition, the processing unit 110 records usage information duringaccessing the pages. For example, the usage information comprises avalid page count table for recording valid page counts of the blocks,respectively. This is for illustrative purposes only, and is not meantto be a limitation of the present invention. According to a variation ofthis embodiment, the usage information comprises an invalid page counttable for recording invalid page counts of the blocks, respectively. Inpractice, as each fully programmed block comprise a predetermined numberof pages (e.g. 128 pages in this embodiment), the valid page count andthe invalid page count of the same fully programmed block arecomplementary to each other.

According to this embodiment, the processing unit 110 records 1 in thefirst field of the valid page count table, in order to indicate that PHYBLK 0 contains 1 valid page (i.e. 1 page of useful data; or in otherwords, 1 page of valid data). Please note that the global page addresslinking table and the valid page count table can be stored in thevolatile memory 120. In this way, the global page address linking tableand the valid page count table can be updated easily during accessingthe flash chips. This is for illustrative purposes only, and is notmeant to be a limitation of the present invention. According to avariation of this embodiment, the global page address linking table andthe valid page count table can be loaded from the volatile memory 120and stored in one or more of the NV memory elements 140_0, 140_1, . . ., and 140_N before shutting down the memory apparatus 100. Moreparticularly, the global page address linking table and the valid pagecount table can be stored in one or more link blocks of the NV memoryelements 140_0, 140_1, . . . , and 140_N. In this way, the global pageaddress linking table and the valid page count table can be preservedwhile the memory apparatus 100 shuts down. Each of the one or more linkblocks is a particular block for preserving system information. Whileturning on the memory apparatus 100 next time, the global page addresslinking table and the valid page count table can be easily obtained fromthe link block(s).

Next, the host sends a command C1 to the memory apparatus 100 in orderto write 4 sectors of data, D_(S4)-D_(S7), into corresponding hostaddresses 0000512-0000515. Similarly, the processing unit 110 determinesthat the logical page addresses of the host addresses 0000512-0000515are all 128 (i.e. all of the host addresses 0000512-0000515 belong toLOG Page 128, or comprise the logical page address 128), and the logicalblock addresses thereof are all 1 (i.e. all of the host addresses0000512-0000515 further belong to LOG BLK 1, or comprise the logicalblock address 1). In addition, the data D_(S4)-D_(S7) should be storedin the first, the second, the third, and the fourth sectors of a page,respectively. Since PHY Page 0 has been programmed, the processing unit110 writes/programs the data D_(S4)-D_(S7) into the first, the second,the third, and the fourth sectors of PHY Page 1 (which is the pagesubsequent to PHY Page 0), respectively. The processing unit 110 furtherrecords 1 in the 129^(th) field of the global page address linking tableshown in FIG. 9A, in order to indicate that LOG Page 128 links to PHYPage 1. In addition, the processing unit 110 records 2 in the firstfield of the valid page count table (i.e. the processing unit 110updates the first field thereof with 2), in order to indicate that PHYBLK 0 contains 2 valid pages (i.e. 2 pages of valid data). That is, theprocessing unit 110 increases the valid page count of PHY BLK 0. This isfor illustrative purposes only, and is not meant to be a limitation ofthe present invention. In a situation where the valid page count tableis replaced by the invalid page count table mentioned above, theprocessing unit 110 maintains a value of an invalid page count of PHYBLK 0.

Please note that the host addresses 0000512-0000515 and the hostaddresses 0000008-0000011 belong to different logical block (e.g. thehost addresses 0000512-0000515 belong to LOG BLK 1, and the hostaddresses 0000008-0000011 belong to LOG BLK 0), however, these hostaddresses all link to the associated pages in the same physical blocks,and data corresponding to the host addresses 0000512-0000515 and datacorresponding to the host addresses 0000008-0000011 are bothprogrammed/written in the same physical block, i.e. PHY BLK 0 in thisembodiment.

In the above situation, when a first set of host addresses (e.g. thehost addresses 0000512-0000515) belong to a first logical block (e.g.LOG BLK 1) and a second set of host addresses (e.g. the host addresses0000008-0000011) belong to a second logical block (e.g. LOG BLK 0), theprocessing unit 110 can program/write both the data corresponding to thefirst set of host addresses and the data corresponding to the second setof host addresses in the same physical block (e.g. PHY BLK 0). This isfor illustrative purposes only, and is not meant to be a limitation ofthe present invention. According to a variation of this embodiment, whena first set of host addresses belong to a first logical block, theprocessing unit 110 can program/write a first portion and a secondportion of the data corresponding to the first set of host addresses indifferent physical blocks wherein the first portion and the secondportion of the data are not overlap.

In this embodiment, the host then sends a command C2 to the memoryapparatus 100 in order to write 4 sectors of data, D_(S8)-D_(S11), intocorresponding host addresses 0000004-0000007. Similarly, the processingunit 110 determines that the logical page addresses of the hostaddresses 0000004-0000007 are all 1 (i.e. all of the host addresses0000004-0000007 belong to LOG Page 1, or comprise the logical pageaddress 1), and the logical block addresses thereof are all 0 (i.e. allof the host addresses 0000004-0000007 further belong to LOG BLK 0, orcomprise the logical block address 0). In addition, the dataD_(S8)-D_(S11) should be stored in the first, the second, the third, andthe fourth sectors of a page, respectively. Since PHY Page 1 has beenprogrammed, the processing unit 110 writes/programs the dataD_(S8)-D_(S11) into the first, the second, the third, and the fourthsectors of PHY page 2 (which is the page subsequent to PHY Page 1),respectively. The processing unit 110 further records 2 in the secondfield of the global page address linking table shown in FIG. 9A, inorder to indicate that LOG Page 1 links to PHY Page 2. In addition, theprocessing unit 110 records 3 in the first field of the valid page counttable (i.e. the processing unit 110 updates the first field thereof with3), in order to indicate that PHY BLK 0 contains 3 valid pages (i.e. 3pages of valid data). That is, the processing unit 110 increases thevalid page count of PHY BLK 0. This is for illustrative purposes only,and is not meant to be a limitation of the present invention. In thesituation where the valid page count table is replaced by the invalidpage count table mentioned above, the processing unit 110 maintains thevalue of the invalid page count of PHY BLK 0.

FIGS. 10A-10F respectively illustrate exemplary versions of the validpage count table of this embodiment. Referring to the left half of FIG.10A first, the ranking of a field of the valid page count tablerepresents a physical block address, and the content of this fieldrepresents an associated valid page count. For example, given thati_(PBLK) and j_(PBLK) are respectively the row number and the columnnumber of the illustrative table location (i_(PBLK), j_(PBLK)) of thevalid page count table and i_(PBLK)=0, 1, . . . , etc. and j_(PBLK)=0,1, . . . , etc. in this embodiment, the illustrative table location(i_(PBLK), j_(PBLK)) corresponding to the (i_(PBLK)*4+j_(PBLK))^(th)field represents a physical block address (i_(PBLK)*4+j_(PBLK)). This isfor illustrative purposes only, and is not meant to be a limitation ofthe present invention. For better comprehension, the valid page counttable can be illustrated as a single column, as shown in the right halfof FIG. 10A. Given that i_(PBLK) is still the row number and i_(PBLK)=0,1, . . . , etc., within this 1-D array illustration of the valid pagecount table, the illustrative table location i_(PBLK) corresponding tothe i_(PBLK) ^(th) field represents a physical block address (i_(PBLK))As a result of executing command C2 in this embodiment, the global pageaddress linking table and the valid page count table are updated asshown in FIGS. 9A and 10A, respectively.

Subsequently, the host sends a command C3 to the memory apparatus 100 inorder to write/update 4 sectors of data, D_(S0)′-D_(S3)′, intocorresponding host addresses 0000008-00000011. Similarly, the processingunit 110 determines that the logical page addresses of the hostaddresses 0000008-00000011 are all 2 (i.e. all of the host addresses0000008-0000011 belong to LOG Page 2, or comprise the logical pageaddress 2), and the logical block addresses thereof are all 0 (i.e. allof the host addresses 0000008-0000011 further belong to LOG BLK 0, orcomprise the logical block address 0). In addition, the dataD_(S0)′-D_(S3)′ should be stored in the first, the second, the third,and the fourth sectors of a page, respectively. Since PHY Page 2 hasbeen programmed, the processing unit 110 writes/programs the dataD_(S0)′-D_(S3)′ into the first, the second, the third, and the fourthsectors of PHY page 3 (which is the page subsequent to PHY Page 2),respectively. The processing unit 110 further records/updates 3 in thethird field of the global page address linking table shown in FIG. 9B,in order to indicate that LOG Page 2 links to PHY Page 3 now. Inaddition, the processing unit 110 still records 3 in the first field ofthe valid page count table shown in FIG. 10B, in order to indicate thatPHY BLK 0 still contains 3 valid pages. That is, the processing unit 110maintains the value 3 of the valid page count of PHY BLK 0. This is forillustrative purposes only, and is not meant to be a limitation of thepresent invention. In the situation where the valid page count table isreplaced by the invalid page count table mentioned above, the processingunit 110 increases the invalid page count of PHY BLK 0.

Although 4 pages, PHY Pages 0-3, have been programmed in PHY BLK 0, only3 physical pages, PHY Page 1-3, contain valid data. Since data of LOGPage 2 has been updated, PHY Page 0 does not contain valid data and canbe deemed as an invalid page containing invalid data. As a result ofexecuting command C3, the global page address linking table and thevalid page count table are updated as shown in FIGS. 9B and 10B,respectively.

In this embodiment, referring to FIGS. 9C and 10C, assume that afterseveral writing/programming operations are further performed, all pagesof the PHY BLK 0 have been programmed, and the valid page count of thePHY BLK 0 is 100. The host sends a command C4 to the memory apparatus100 in order to write/update 4 sectors of data, D_(S0)″-D_(S3)″, intocorresponding host addresses 0000008-00000011. Similarly, the processingunit 110 determines that the logical page addresses of the hostaddresses 0000008-00000011 are all 2 (i.e. all of the host addresses0000008-0000011 belong to LOG Page 2, or comprise the logical pageaddress 2), and the logical block addresses thereof are all 0 (i.e. allof the host addresses 0000008-0000011 further belong to LOG BLK 0, orcomprise the logical block address 0). In addition, the dataD_(S0)″-D_(S3)″ should be stored in the first, the second, the third,and the fourth sectors of a page, respectively. Since all pages of thePHY BLK 0 have been programmed, the processing unit 110 writes/programsthe data D_(S0)″-D_(S3)″ into the first, the second, the third, and thefourth sectors of PHY page 128 (which is the page subsequent to PHY Page127), respectively. The processing unit 110 further records/updates 128in the third field of the global page address linking table shown inFIG. 9D, in order to indicate that LOG Page 2 links to PHY Page 128 now.Here, PHY Page 3 does not contain valid data and can be deemed as aninvalid page containing invalid data. In addition, the processing unit110 records 1 in the second field of the valid page count table toindicate that PHY BLK 1 contains 1 valid page (i.e. 1 page of validdata), and records/updates 99 in the first field of the valid page counttable to indicate that PHY BLK 0 contains 99 valid pages (i.e. 99 pagesof valid data) now. That is, the processing unit 110 decreases the validpage count of PHY BLK 0. This is for illustrative purposes only, and isnot meant to be a limitation of the present invention. In the situationwhere the valid page count table is replaced by the invalid page counttable mentioned above, the processing unit 110 increases the invalidpage count of PHY BLK 0.

As a result of executing command C4, the global page address linkingtable and the valid page count table are updated as shown in FIGS. 9Dand 10D, respectively.

Next, the host sends a command C5 to the memory apparatus 100 in orderto read 4 sectors of data corresponding host addresses 0000008-00000011.The processing unit 110 parses the command C5 to execute the readingoperation. The processing unit 110 transfers the host addresses0000008-0000011 into logical addresses. The processing unit 110 dividesthe host address 0000008 by the number of sectors of a page, i.e. 4 inthis embodiment, and obtains a quotient 2 and a remainder 0. Thequotient 2 means that the logical page address thereof is 2, where thelogical page indicated by the logical page address 2 is LOG Page 2. Inaddition, the remainder 0 means that the data D_(S0) should have beenstored in the first sector of a page. Similarly, the processing unit 110determines that the logical page addresses of the host addresses0000009, 0000010, and 0000011 are all 2 (i.e. all of the host addresses0000009, 0000010, and 0000011 belong to LOG Page 2, or comprise thelogical page address 2), and the logical block addresses thereof are all0 (i.e. all of the host addresses 0000009, 0000010, and 0000011 furtherbelong to LOG BLK 0, or comprise the logical block address 0). Inaddition, the data corresponding to host addresses 0000008-00000011should have been stored in the first, the second, the third, and thefourth sectors of a page, respectively. The processing unit 110 readsthe third field of the global page address linking table and obtains128, which indicates that the data corresponding to LOG Page 2 is storedin PHY Page 128. The processing unit 110 reads PHY Page 128 to obtaindata D_(S0)″-D_(S3)″, and sends these data to the host.

In this embodiment, assume that after a lot of writing/programmingoperations are further performed, all blocks of the data region (e.g.PHY BLKs 0-4093) have been fully programmed, and the spare regioncomprises PHY BLKs 4094 and 4095, where the valid page count table isillustrated in FIG. 10E. Then, the host sends a command C6 to the memoryapparatus 100 in order to write 4 sectors of data, D_(S12)-D_(S15). Theprocessing unit 110 pops a physical block from the spare region, such asPHY BLK 4094, for writing data D_(S12)-D_(S15). In general, it issuggested to maintain a sufficient block count of the spare region. Forexample, the minimal block count should be always greater than zero. Inanother example, the minimal block count should be greater than zero formost of the time, where the minimal block count can temporarily reachzero as long as the operations of the memory apparatus 100 will not behindered.

Assuming that maintaining a sufficient block count of the spare regionis required in this embodiment, in a situation where the block count ofthe spare region is (or will be) less than a predetermined value (e.g.the predetermined value is 2), the processing unit 110 has to erase aphysical block in the data region, in order to push this erased physicalblock into the spare region. The processing unit 110 searches the validpage count table and finds out that PHY BLK 2 has no valid data sincethe valid page count of PHY BLK 2 is 0. Since, PHY BLK 2 having theleast valid page count, the processing unit 110 erases the PHY BLK 2 andthen pushes the erased PHY BLK 2 into the spare region. Thus, the spareregion comprises PHY BLKs 2 and 4095 now. This is for illustrativepurposes only, and is not meant to be a limitation of the presentinvention. According to a variation of this embodiment, when the validpage count of PHY BLK 2 decreases to zero, the processing unit 110 canerase PHY BLK 2 immediately.

According to this embodiment, assume that after severalwriting/programming operations are further performed, all pages of thePHY BLK 4094 have been programmed, where the valid page count table isillustrated in FIG. 10F. Then, the host sends a command C7 to the memoryapparatus 100 in order to write 4 sectors of data, D_(S16)-D_(S19). Theprocessing unit 110 pops a physical block from the spare region, such asPHY BLK 4095, for writing data D_(S16)-D_(S19).

Similarly, when it is detected that the block count of the spare regionis (or will be) less than the predetermined value, the processing unit110 has to erase at least a physical block in the data region in orderto push the physical block(s) into the spare region. The processing unit110 of this embodiment searches the valid page count table shown in FIG.10F and finds out that PHY BLK 0 has 40 pages of valid data and PHY BLK1 has 50 pages of valid data, where PHY BLKs 0 and 1 have the leastvalid page counts among others. In this embodiment, the processing unit110 moves the valid data of PHY BLKs 0 and 1 into PHY BLK 2, and updatesthe global page address liking table to reflect the movement of thevalid data. In other words, the processing unit 110 reads the valid datain PHY BLKs 0 and 1, programs/writes the valid data into PHY BLK 2, andlinks the logical page addresses of the valid data to the physical pagesprogrammed/written with the valid data, correspondingly. After movingthe valid data, the processing unit 110 erases PHY BLKs 0 and 1, andpushes the erased PHY BLKs 0 and 1 into the spare region.

In this embodiment, when it is detected that the block count of thespare region is less than the predetermined value, the processing unit110 typically searches the valid page count table to find one or morefully programmed blocks having the least valid page count(s), and erasesthe one or more fully programmed blocks in order to push the one or moreblocks into the spare region. This is for illustrative purposes only,and is not meant to be a limitation of the present invention. Accordingto a variation of this embodiment, in a situation where the valid pagecount table is replaced by the invalid page count table mentioned above,the processing unit 110 can search the invalid page count table to findone or more fully programmed blocks having the most invalid pagecount(s), and erase the one or more fully programmed blocks of thisvariation in order to push the one or more blocks into the spare region.

According to this embodiment, the processing unit 110 has popped onemore physical block from the spare region into the data region, such asPHY BLK 2, for merging PHY BLKs 0 and 1. This is for illustrativepurposes only, and is not meant to be a limitation of the presentinvention. According to a variation of this embodiment, the processingunit 110 can merge the one or more fully programmed blocks having theleast valid page count(s) into a partially programmed block as long asthere are enough free pages in the partially programmed block, where thefree pages represent the pages that have not been programmed since thelatest erasure of the block comprising these valid pages. For example,the processing unit 110 can merge PHY BLKs 0 and 1 into the partiallyprogrammed block, such as PHY BLK 4095, as long as there are enough freepages in the partially programmed block for programming dataD_(S16)-D_(S19) and the valid data of PHY BLKs 0 and 1. In anotherexample, the processing unit 110 can merge PHY BLK 0 into the partiallyprogrammed block, such as PHY BLK 4095, as long as there are enough freepages in the partially programmed block for programming dataD_(S16)-D_(S19) and the valid data of PHY BLK 0.

In practice, the processing unit 110 can program/write the dataD_(S16)-D_(S19) into PHY BLK 4095, and can further move the valid dataof PHY BLKs 0 and 1 into PHY BLK 4095 as long as there are enough freepages in PHY BLK 4095 for programming data D_(S16)-D_(S19) and the validdata. Certainly, the processing unit 110 of this variation updates theglobal page address liking table to reflect the movement of the validdata. Similarly, after moving the valid data, the processing unit 110erases PHY BLKs 0 and 1, and pushes the erased PHY BLKs 0 and 1 into thespare region.

In other variations of this embodiment, the processing unit 110 can movevalid data of N physical blocks into M physical blocks wherein N and Mare positive integers, and N is greater than M. Assume that there are Kpages of valid data in total within the N physical blocks, where K issmaller than the number of free pages in total within the M physicalblocks. The processing unit 110 can read the K pages of valid data fromthe N physical blocks, erase the N physical blocks, buffer the K pagesof valid data into the volatile memory 120, and program/write the Kpages of valid data into the M physical blocks. Please note that, ingeneral, the N physical blocks and the M physical blocks may overlap(e.g. the N physical blocks and the M physical blocks both comprise atleast a same physical block) or not overlap. In a situation where the Nphysical blocks and the M physical blocks do not overlap (i.e. none ofthe N physical blocks belongs to the M physical blocks, and vice versa),the K pages of valid data can be programmed/written into the M physicalblocks without waiting for erasing the N physical blocks, and theprocessing unit 110 can generate (N−M) erased blocks eventually.Certainly, the processing unit 110 updates the global page addressliking table to reflect the movement of the valid data.

Please note that, in other variations of this embodiment, the processingunit 110 can record the invalid page count of each physical block. Forexample, given that the page count of each physical block is 128, aspecific physical block comprises 128 pages, within which 28 pages areinvalid pages containing invalid data and 100 pages are valid pagescontaining valid data. That is, the invalid page count and the validpage count of the specific physical block are 28 and 100, respectively.The processing unit 110 can build an invalid page count table of theflash chips 0-3, and erase a particular physical block according to theinvalid page count table. In some of the variations, when the processingunit 110 has to erase a physical block, the processing unit 110 canselect a particular physical block having the most invalid pagesaccording to the invalid page count table, and erase the particularphysical block. In practice, before the particular physical is erased,the valid data contained therein have to be moved to other blocks. Forefficiently moving the valid data, the processing unit 110 can recordone or more positions of the valid data in the particular block. Moreparticularly, the processing unit 110 can build a valid-page-positiontable for each block in order to indicate the position(s) of one or morevalid pages containing valid data within the block.

FIG. 11 illustrates a valid-page-position table of the flash chips 0-3according to an embodiment of the present invention. The arrangement ofthe illustrative table locations of valid-page-position table is similarto that of FIGS. 10B-10F together with the right half of FIG. 10A, andtherefore, is not explained in detail for simplicity. In thisembodiment, each field of the valid-page-position table indicateswhether any valid-page-position corresponding to an associated physicalblock exists. For example, each field of this embodiment comprises 128bits respectively corresponding to the pages of the associated physicalblock.

In particular, each field of the valid-page-position table indicates thevalid-page-position(s) corresponding to the associated physical block.Each bit in a specific field indicates whether an associated page in theassociated physical block is valid or invalid. For example, the firstfield of the valid-page-position table shown in FIG. 11 is recorded as“01011100101 . . . 11111”, which indicates the valid-page-position(s)within PHY BLK 0.

More specifically, the ranking of a specific bit in the specific fieldof the valid-page-position table shown in FIG. 11 represents a pageaddress offset (or a relative page position) of an associated pagewithin the associated physical block. For example, regarding the bits“01011100101 . . . 11111” in the first field of the valid-page-positiontable shown in FIG. 11, the least significant bit (LSB) “1” indicatesthat the first page of the PHY BLK 0 (i.e. the PHY Page 0) is a validpage containing valid data, and the most significant bit (MSB) “0”indicates that the last page of the PHY BLK 0 (i.e. the PHY Page 127) isan invalid page containing invalid data, where other bits between LSBand MSB indicate the valid/invalid state of the other physical pages ofthe associated physical block, respectively. Similar descriptions arenot repeated for the other fields of the valid-page-position table shownin FIG. 11. As a result, the processing unit 110 can move valid datacontained in the valid pages quickly according to thevalid-page-position table.

In this embodiment, the LSB in the specific field indicates whether thefirst page of the associated physical block is a valid page or aninvalid page, and the MSB in the specific field indicates whether thelast page of the associated physical block is a valid page or an invalidpage. This is for illustrative purposes only, and is not meant to be alimitation of the present invention. According to a variation of thisembodiment, the LSB in the specific field indicates whether the lastpage of the associated physical block is a valid page or an invalidpage, and the MSB in the specific field indicates whether the first pageof the associated physical block is a valid page or an invalid page. Forexample, regarding the bits “01011100101 . . . 11111” in the firstfield, the LSB “1” indicates that the last page of the PHY BLK 0 (i.e.the PHY Page 127) is a valid page containing valid data, and the mostsignificant bit (MSB) “0” indicates that the first page of the PHY BLK 0(i.e. the PHY Page 0) is an invalid page containing invalid data, whereother bits between LSB and MSB indicate the valid/invalid state of theother physical pages of the associated physical block, respectively.

In this embodiment, a logical value “1” of the specific bit indicatesthat the associated page is a valid page, while a logical value “0” ofthe specific bit indicates that the associated page is an invalid page.This is for illustrative purposes only, and is not meant to be alimitation of the present invention. According to a variation of thisembodiment, the logical value “0” of the specific bit indicates that theassociated page is a valid page, while the logical value “1” of thespecific bit indicates that the associated page is an invalid page.

In addition, the valid-page-position table can be stored in the volatilememory 120. In this way, the valid-page-position table can be updatedeasily during accessing the flash chips. This is for illustrativepurposes only, and is not meant to be a limitation of the presentinvention. According to a variation of this embodiment, thevalid-page-position table can be loaded from the volatile memory 120 andstored in one or more of the NV memory elements 140_0, 140_1, . . . ,and 140_N before shutting down the memory apparatus 100. Moreparticularly, the valid-page-position table can be stored in one or morelink blocks of the NV memory elements 140_0, 140_1, . . . , and 140_N.In this way, the valid-page-position table can be preserved while thememory apparatus 100 shuts down. While turning on the memory apparatus100 next time, the valid-page-position table can be easily obtained fromthe link block(s).

In another embodiment, during accessing the memory apparatus 100, thevalid-page-position table and global page address linking table can beloaded from the volatile memory 120 and stored in the NV memory elementsfrom time to time. For example, the valid-page-position table and globalpage address linking table can be stored in every predetermined timeperiod (e.g. 2 second) or in every predetermined accessing operations(e.g. 100 times of writing). When the memory apparatus 100 is abnormallyshutting down, the latest valid-page-position table and global pageaddress linking table are not loaded from the volatile memory 120 andstored in the NV memory elements. Then, the memory apparatus 100 isturning on. For building the valid-page-position table, the processingunit 110 can search the blocks that have been accessed after the latestupdating of the valid-page-position table and global page addresslinking table in the NV memory elements. The processing unit 110searches logical page addresses stored in each page of these blocks tobuild and update the global page address linking table. After that, thevalid-page-position table can be built according to the updated globalpage address linking table.

In contrast to the related art, the present invention method andapparatus can greatly save the time of building logical-to-physical pageaddress linking table(s), such as the global page address linking table.Therefore, the present invention provides better performance than therelated art.

It is another advantage of the present invention that the presentinvention method and apparatus can record the usage information duringaccessing the pages, and therefore can efficiently manage the usage ofall blocks according the usage information. As a result, the arrangementof the spare region and the data region can be optimized.

In addition, managing the flash memory on a basis of page brings lots ofadvantages. For example, the speed of random write is greatly improved,and the write amplification index can be greatly reduced. Withoutintroducing side effects such as those of the related art, managing theflash memory on a basis of page can be much simpler and more intuitionalthan managing the flash memory on a basis of block as long as thepresent invention is applied in real implementation.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

1. A method for managing a memory apparatus, the memory apparatuscomprising at least one non-volatile (NV) memory element, each of whichcomprises a plurality of blocks comprising a plurality of pages,respectively, the method comprising: recording valid/invalid pageposition information of at least one block; and moving valid datacontained in at least a valid page of the block according to thevalid/invalid page position information; wherein the block is an erasingunit.
 2. The method of claim 1, wherein the valid/invalid page positioninformation contains relative position information of the valid data inthe block.
 3. The method of claim 2, wherein the valid/invalid pageposition information contains a plurality of bits, the ranking of eachbit represents a page address offset of each page within the block, andeach bit respectively indicates whether each page in the block is validor invalid.
 4. The method of claim 1, further comprising: storing thevalid/invalid page position information into the NV memory elementbefore shutting down the memory apparatus.
 5. The method of claim 1,wherein the step of recording the valid/invalid page positioninformation of the at least one block further comprises: searching apage address linking table after turning on the memory apparatus.